JPH0761524B2 - Method for forming tubular body - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a tubular body, and more particularly to a method for forming a deformed tubular body in which at least the inner shape of a circular tubular body is formed into different shapes.

2. Description of the Related Art In the conventional method for forming a deformed tubular body, it is necessary to prepare a dedicated forging tool according to the intended final product shape. For example, when molding a blind nut with a hexagonal outer shape, first use a pressing machine or a forging machine to make a hexagonal rod-shaped body, and then make a flange at one end, and then cut the hexagonal hole or circular hole in half from the flange side. A predetermined blind nut is formed by forming a circular hole from the opposite end, then penetrating the two holes, and then forming an internal thread in the circular hole portion.

Further, when a blind nut having a hexagonal outer shape is formed by using a cylindrical body having a circular outer shape, a hexagonal punch is pushed into the tubular body, and at the same time, a cylindrical shape is formed with six jigs from the outside. Pressing the sides of the body is done.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-mentioned conventional method for forming a deformed tubular body, since the forging die tool is different depending on the shape of the hole of the tubular body, the same type of die tool cannot be used. For this reason, it is necessary to prepare mold tools of various shapes, which has a drawback of increasing the cost of the final product. Also, when a hexagonal tubular body is formed from a circular tubular body, a special jig is required, which has a drawback of increasing the cost of the product.

Therefore, an object of the present invention is to provide a method for easily molding a circular tubular body to a deformed tubular body such as a hexagon at low cost.

Means for Solving the Problems In order to achieve such an object, according to the present invention, there is provided a method for forming a circular tubular body into an irregularly shaped tubular body, wherein a flange is formed at one end of a circular rod-shaped body, A circular rod-shaped body is formed with a circular first hole halfway from the side of the flange, and has a diameter slightly smaller than the first hole from the end of the rod-shaped body on the side opposite to the flange to the front of the first hole portion. 2nd hole is formed, and the circular rod-shaped body is inserted into the hole of the die from the end opposite to the flange until the flange contacts the die, and the punch is inserted from the first hole portion of the circular rod-shaped body. Push it in,
The outer shape and inner shape of the first hole portion are deformed from a circular shape to a hexagonal shape, and the outer shape and inner shape of the second hole portion are kept circular while allowing the first hole to communicate with the second hole. A method for forming a tubular body is provided, which comprises:

Further, according to the present invention, there is provided a method for forming an inner shape of a circular tubular body into a deformed tubular body, wherein a flange is formed at one end of the circular rod-shaped body, and the circular rod-shaped body is rounded from the flange side. The first hole of the rod is formed halfway, and the first hole is formed from the end of the rod-shaped body on the side opposite to the flange to the front of the first hole.
A circular second hole having a diameter slightly smaller than the hole is formed, and the circular rod-shaped body is inserted into the hole of the die from the end opposite to the flange until the flange comes into contact with the die, and the punch is inserted into the circular rod-shaped body. While pushing from the first hole portion to form a plurality of notches extending in the longitudinal direction inside the first hole portion to deform the inner shape, while maintaining the outer shape and the inner shape of the second hole portion as they are. A method for forming a tubular body is provided, which comprises connecting the first hole to the second hole.

Examples Examples of the present invention will be described below with reference to the drawings. FIGS. 1 (a) to 1 (e) are modified tubular shapes in the case of a blind nut starting from a circular rod-like body and finally the flange side portion is formed into a hexagonal outer shape and inner shape. The body forming method is shown in FIG. 2 (a).
And (b) shows a blind nut molded by this method. Hereinafter, each step will be described in order.

First, as shown in FIG. 1 (a), a circular rod-shaped body 1 is prepared, and a flange 2 is formed at one end of this rod-shaped body 1 as shown in FIG. 1 (b). Next, as shown in FIG. 1 (c), a circular hole 3 is formed from the side of the flange 2 by about half to 2/3.
Make up to a certain position. As described above, the shape of the final blind nut is such that the inner shape of the portion of the hole 3 is also hexagonal, but according to the method of the present invention, the shape of the hole 3 may be circular at this stage. Please note that. Therefore, it will be understood that a specially shaped jig is not required as in the conventional molding method. Thereafter, as shown in FIG. 1 (d), a circular hole 4 having a diameter slightly smaller than the hole 3 is formed from the opposite end portion. The molding of the hole 4 is similar to the conventional molding method.

In the present invention, in the step of FIG. 1 (e), the die 5 and the punch 6 are used to change the outer shape of the circular tubular body 7 and the inner shape of the hole 3 to be an intermediate product shown in FIG. 1 (d) to a circular shape. To a hexagon. That is, the die 5 has a hole 8 having a hexagonal internal shape and having a size into which the main body of the circular tubular body 7 can be inserted, and the main body of the circular tubular body 7 is inserted into the die hole 8. In this state, the punch 6 is pushed into the hole 3 of the tubular body 7.

The punch 6 has a small-diameter portion 9 through which the holes 3 and 4 of the tubular body 7 penetrate, and a body portion 10 which is slightly smaller than the die hole 8 but slightly larger than the hole 3 and formed into a hexagon. ing. Therefore, as shown in FIGS. 2A and 2B, in the blind nut 11 as the final product, the lower surface portion 12 of the flange 2 is formed into a hexagon and the inner shape of the hole 3 is also formed into a hexagon. Molded. Thus, according to the tubular body molding method of the present invention, a circular rod-shaped body is molded into a hexagonal tubular body. In addition, in the hole 4 of the blind nut 11,
A predetermined internal thread is molded.

3 (a) and 3 (b) show an example of molding a tubular body having a shape different from that of FIG. 1 by using the tubular body molding method according to the present invention. In this example, the dice 14
The hole 15 is formed in a circular shape, and the main body portion 17 of the punch 16 is formed with protrusions 18 having a triangular cross section at every 90 ° of its outer peripheral surface. As described in FIG. 1, the circular tubular body 7
Then, the circular tubular body 7 of FIG.
Hole 15 of the circular tubular body 7 and punch 16 into the hole 4 of the circular tubular body 7.
Is pushed in as shown in FIG. 3 (b). This allows
As shown in FIGS. 4 (a) and 4 (b), the blind nut 20 as a final product has four sharp cuts 19 formed inside thereof, so that a tubular body having an irregular inner shape can be molded. .

FIGS. 5 (a) and 5 (b) show four sharp cuts inside the rivet body 21 of a blind rivet using a die and punch similar to the one shown in FIG.
22 shows an example in which 22 is molded into a deformed tubular body.

By forming a sharp cut as shown in FIGS. 4 and 5 above, the blind nut and blind rivet make it easier to buckle the tubular body portion of the lower surface portion of the flange, and the work of fixing is extremely difficult. There is an advantage that it is done easily.

EFFECTS OF THE INVENTION According to the present invention, it is easy to insert the circular tubular body into a die having a hole having a size to receive the circular tubular body, and press a punch having an outer shape of a predetermined shape into the hole of the circular tubular body. It is possible to extremely easily form a tubular body having a desired shape by performing various operations. In addition, in the conventional molding method, in order to mold the inner shape into a desired shape, it was necessary to prepare many kinds of jigs having special shapes in accordance with the shape. According to this, it is only necessary to first form a simple circular hole, and therefore, punches and dies for forming need not be expensive. Also, when molding into the final shape, since it is sufficient to prepare a simple shape, there is an advantage that the price of the tubular body as the final product does not become expensive. Particularly, according to the present invention, the flange is formed at one end of the circular rod-shaped body, and therefore, the circular rod-shaped body is inserted into the hole of the die from the end opposite to the flange until the flange comes into contact with the die. The desired tubular body can be obtained by an extremely simple operation of pushing the punch from the first hole portion of the circular rod-shaped body, and the blind nut and blind rivet can be easily obtained at low cost.

[Brief description of drawings]

1 (a) to 1 (e) are explanatory views showing each step of the method for forming a tubular body according to the present invention, and FIGS. 2 (a) and 2 (b) are each formed by the forming method according to the present invention. The plan view and the half-section front view of the blind nut are shown in FIGS. 3 (a) and 3 (b) respectively before and after the step of forming a circular tubular body using a punch and a die different from those in the example of FIG. Explanatory views, FIGS. 4 (a) and (b) are a plan view and a half-section front view of the blind nut molded by the molding method of FIG. 3, and FIGS. 5 (a) and (b) are respectively,
FIG. 4A is a plan view and a half-section front view of a blind rivet body molded by the molding method of FIG. DESCRIPTION OF SYMBOLS 1 ... Rod, 2 ... Flange 3 ... Flange side hole, 4 ... Opposite side hole 5 ... Die, 6 ... Punch 7 ... Circular tubular body, 8 ... Die hole 10 ...... Punch body part 11 ...... Blind nut 14 …… Die, 15 …… Die hole 16 …… Punch, 17 …… Punch body part 18 …… Projection, 19 …… Cut 20 …… Blind nut 21 …… Blind Rivet body 22 ... notch

Claims (2)

[Claims] 1. A method for forming a circular tubular body into an irregularly shaped tubular body, wherein a flange is formed at one end of a circular rod-shaped body, and a circular first hole is formed in the circular rod-shaped body halfway from the flange side. Then, a circular second hole having a diameter slightly smaller than the first hole is formed from the end of the circular rod-shaped body on the side opposite to the flange to the front of the first hole portion, and the circular rod-shaped body is formed in the hole of the die. Insert the punch from the end on the opposite side of the flange until the flange contacts the die, and push the punch from the first hole portion of the circular rod-shaped body to change the outer shape and inner shape of the first hole portion from the circular shape. A method of forming a tubular body, which comprises deforming to a hexagon and allowing the first hole to communicate with the second hole while maintaining the outer shape and the inner shape of the second hole portion in a circular shape. 2. A method for forming an inner shape of a circular tubular body into a deformed tubular body, wherein a flange is formed at one end of the circular rod-shaped body, and a circular first hole is formed in the circular rod-shaped body from the side of the flange. Form a halfway, form a circular second hole slightly smaller than the first hole from the end of the rod-shaped body on the side opposite to the flange to just before the first hole portion, and insert the circular rod-shaped hole into the hole of the die. The body is inserted from the end opposite to the flange until the flange contacts the die, and the punch is pushed through the first hole portion of the circular rod-shaped body and extends in the longitudinal direction inside the first hole portion. A plurality of notches are formed to deform the inner shape, and the first hole is formed into the second hole while maintaining the outer shape and the inner shape of the second hole portion as they are.
A method for forming a tubular body, comprising forming a tubular body.